Epidemiology of rickettsial diseases of animals in India: Temporal and spatial distribution

Epidemiology of Rickettsial diseases of

animals in India- Temporal and Spatial

DistributionRadhakrishna SahuDivision of Veterinary Public Health

&

Bhoj R SinghDivision of Epidemiology

Indian Veterinary Research Institute Izatnagar-243122

Rickettsia

• Prokaryotes• Resemble characteristics of both bacteria and

virus• It’s smaller than bacteria and larger than

virus

Like bacteria• Contains both DNA &

RNA• Multiply through

binary fission• Staining reaction (Gram

negative organisms)

Like virus• Obligate intracellular

parasites• Can’t be cultured in artificial

media• Requires living cells or

embryonated eggs for growth and isolation

RickettsiaProkaryotes, resembling with both bacteria and virus in their characteristics. There are smaller than bacteria and larger than virus.

Rickettsia: A big groupFamily –RickettsiiaceaeGenus-

-Ehrlichia-Orientia-Coxiella (now excluded)-Rickettsia (Typhus group and Spotted Fever

Group)-Neorickettsia-Anaplasma-Bartonella quintana (Now excluded)

Ehrlichia

In Canines- Ehrlichia canis (Canine Rickettsiosis)

& E. ewingii (Canine Granulocytic Ehrlichiosis)

In Cattle- E. ruminatum (Heart Water Disease)

In Human- E. chaffensis (Human Monocytic Ehrlichiosis)

Canine Ehrlichiosis• Also known as Canine Rickettsiosis/ Canine

Haemorrhagic Fever/ Canine Typhus/ Tropical Canine Pancytopaenia

• Transmitted by Brown dog tick (Riphicephalus sanguinus) and Deer tick (Ixodes scapularis)

• Iatrogenic transmission through blood transfusion• Most of the cases occurs during spring and summer• Widely prevalent in tropical and sub-tropical countries• Dog (particularly German Shepherd) & cats are more

susceptible for infection

Ehrlichiosis appears in 3 phases1. Acute Phase- Characterised by fever,

petechiae, bleeding Disorders, vasculitis, lymphadenitis, oedema of lungs.

2. Chronic Phase- It is associated with weight loss, pale gum, thrombocytopenia, polyurea, dyspnoea, lameness, ophthalmic disease. Mortality is high in chronic phase.

3. Sub-clinical phase- In this form no sign and symptoms, the dog may remain carrier for whole life.

Pathogenesis• It infects monocytes of peripheral blood and

subsequently affects mononuclear phagocytic system (MPS ) throughout the body.

• Thrombocytopenia occurs due to consumption of platelet, immune mediate destruction of platelets, sequestering of platelets, decreased production in bone marrow. Decreased blood cell count occurs due to bone marrow depression mostly in chronic phase.

• Sometimes co-infection with Babesia and Hepatozoan canis also occurs to complicate the disease.

Ehrlichiosis

Diagnostic tests for Ehrlichiosis

• Serological assays• PCR• Blood smear test (Not suitable for sub-clinical

and chronic phase)• IFA, a standard diagnostic test

Ehrlichia organism in MonocyteBy Courtesy of S. Dhankar, R.D. Sharma, N. Jindal. Seroepidemilogical survey of canine Ehrlichiosis in Delhi and Haryana states.

Indian Scenario

• In India 1st cases was reported in Punjab (Juyal et. al., 1992)

• 47 cases were reported in Kolkata between May 2011- June 2012 (Das et. al., 2013)

• Many serological surveys are conducted in Haryana, Delhi, Maharastra ( Nagpur & Mumbai), Chennai, Gujurat, Punjab and indicated prevalence of infection.

Prevalence based on Peripheral Blood-Smear test

Nagpur Haryana Chennai Ranchi Punjab Mumbai0

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Prevalence based on DOT-ELISA & Nested PCR

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Heart Water Disease

• Also known as Cowdriosis/ Ehrlichiosis, and is caused by Ehrlichia ruminantium (Cowdria ruminantium).

• Spread through Bont long tick (Ambylomma) bites contaminated with saliva or regurgitated gut contents of the ticks.

• Reported in cattle, sheep, goat, antelopes and buffaloes.

• More common in young animal than in aged.• Indigenous cattle are comparatively resistant.

Clinical Heart Water Disease• Fluid get collected around (pericardiac fluid) heart to muffle the heart

sound and lungs of animal get congested due to increased vascular permeability.

• Neurological signs like tremors, head pressing are common.• Respiratory signs like coughing and nasal discharge are apparent.• Fever associated with petechiae on mucous membrane are often

observed.• During post-mortem: Straw coloured fluid is excess is present around

heart (pericardial space) which clots on exposure to air due to high fibrinogen content.

• Microscopic examination of blood smears can reveal extracellular Elementary bodies (Smaller in size, Infective stage), Reticulated body of Large size and Intermediate body.

Severe Lung Edema Edema of Cerebral Grey Matter

Hydropericardium

From: http://www.afrivip.org/sites/default/files/HW/diagnosis.html

Not Reported in India• Common in Sub-Saharan Africa & West-Indian

Island (Zanzibar, Madagascar, Saotome, Mauritius, Reunion)

• No clinical report in India till date.Diagnosis

Demonstration of colony in cytoplasm of capillaries and endothelial cells of brain seen in Squash smear of cerebral grey matter stained with Romanowsky Stain.Immunoperoxidase method for Formaline Fixed Tissues. Differential diagnosis is needed to avoid False +ve (may be confused with Chlamydia pecorum).

Anaplasma and anaplasmosis

1. Anaplasma marginale/ A. caudatum ( Cause Bovine Anaplasmosis)

2. A. phagocytophilum (Canine Ehrlichiosis)3. A. platys (Canine Ehrlichiosis)4. A. centrale (infect cattle)5. A. ovis ( Affect sheep, deer, goat and other

antelopes)

Bovine Anaplasmosis• Previously known as Gall Sickness• Mostly Caused by Anaplasma marginale however A.

centrale, A. bovis may also cause clinical infection.• Bos indicus are more resistant than Bos taurus.• 17 different tick vectors (Boophilus microplus is the most

important in India followed by Hyalomma anatolicum)• Mechanical carriers are Tabanus spp. and Musca spp.

flies.• Prevalent in South and Central America, USA, Southern

Europe, Africa and Asia.

Distribution of Disease• Inverse age resistance- Calves are more

resistant to clinical disease (but not to infection)

• <1yr- Sub-clinical• 1-2yr- Moderately severe• Older cattle- Severe and fatal

Clinical signs

Disease is seen in different forms• Per-acute- Death within few hours of clinical signs• Acute- decreased milk production, inappetance,

rapid breathing, brown colour urine, mucous membranes are pale and yellow, abortion in pregnant animals common.

• Macrocytic Normochromic Anaemia (Destruction of both infected and non-infected erythrocytes due to phagocytosis).

Prevalence of Anaplasmosis Through Microscopy (19.51%), With ELISA (31.71%)By PCR (42.39%) (Sharma et al. 2014)

&

Through Microscopy (11.25%), By PCR (48.75%) (Ashuma et al. 2012)

Prevalence Study in Punjab

• Bos indicus are more resistant to disease but acts as a carrier (Firozpur, with microscopy 16% while with PCR 80% (Ashuma et al. 2012)

• Buffaloes act as a potent source of infection being carrier (nearly 18.18% +ve in PCR, Ashuma et al. 2012)

• Use of infected needles for medication may be a source of infection (as in Patiala & Ludhiana) (Ashuma et al. 2012)

• Less prevalent in Oxytetracycline and acaricides used areas (Ashuma et al. 2012)

• Sub-mountain zones are at higher risk because these are semi humid region which favours vector (Sharma et al. 2014)

Prevalence of Anaplasmosis

Prasanna kumar et al. (2010) reported 46.9% Overall prevalence of the diseases in Hisar and adjacent areas of Bhiwani District, but more on Large organized dairy farms (59.2%). Probably due to availability of large quantity of water which increases moisture, increase in Boophilus ticks and easier transmission due to bigger herd size.

Detected in animals of commercial dairy sectors (46.07%), Gaushalas (44.1%) and Small hold dairy units (35%) (Transmission is not that easier due to smaller herd size and scattered population)

High prevalence without any clinical disease indicates endemic stability.

Prevalence of Anaplasmosis

Prevalence studies in other parts of India

• Tamilnadu- 2.64% (Velusamy et. al., 2014)• Northen Kerala- A. marginale (16.67%) & A.

bovis (3.33%) (Nair AS et. al., 2013)

• Kancheepuram- 18.9% & Chennai- 12.9% (Arunkumar et. al., 2013)

• Myesore (1.51%), Mandya (0.95%), neighbouring district of Bangalore(2.31%) (Krishna Murthy et. al., 1994, Muraleedharan et. al., 2005)

Canine Anaplasmosis

• Anaplasma phagocytophillus and A. platys• Causes lameness (Confused with Lyme Disease)• A. platys causes thrombocytopenia, bruise in

gum and belly and spontaneous nose bleeding• Transmitted mainly by Deer fly.

Canine Anaplasmosis In India…..

• A. phagocytophillum infection is reported from North East India (4.71%) with highest prevalence in pet dogs (6.09%) (Borthakur et. al., 2014)

• A. platys infection cases (27 ) were confirmed in Referral Poly Clinic, Indian Veterinary Research Institute, Izatnagar, Bareilly (UP), mostly having co-infection with E. canis, Babesia gibsoni, B canis (Kumar and Varshney et. al., 2007)

Neorickettsia• N. risticii (Formerly known as Ehrlichia risticii)

causes Potomac Horse Fever/ Shasta Fever/ Equine Monocytic Ehrlichiosis.

• The disease was 1st described in Potomac River area, Washington in 1980

• It is vector borne disease. Vectors are freshwater snails and trematodes released from the snails.

• Found in US, Canada, Europe, India.

• The disease appears as acute enterocolitis syndrome (mild colic, fever, and diarrhoea).

• Infection of enterocytes of the small and large intestine.

• Often precipitates in spring, summer, and early fall and is associated with pastures bordering creeks or rivers.

• In pregnant mares, abortion, due to foetal infection, may be seen.

• Leucopoenia and thrombocytopenia is observed on blood examination.

Potomac Horse Fever

Potomac Horse Fever Diagnosis

• Isolation or identification of N. risticii from the blood or faeces of infected horses in cell culture (mouse macrophage cell line P388D1, or cos-7 cell line or canine myelocytic leukemia cell line DH82).

• PCR using specific primers.• Serologic testing is of limited value because

of false positive reaction.

• N. helminthoeca causes Salmon poisoning in Dog.• It has been reported from Oregon, California, Washington and

India.• Spread through snail-fish-dog cycle. Its specific vector is a fluke

Nanophyetus salmincola.• Clinical signs appear 5–7 days after eating infected fish, and

persist for 7–10 days.• There may be up to 90% mortality among untreated animals.• Infection affects the lymphoid tissues and intestines and is

associated with enlargement of the GI lymphoid follicles, lymph nodes, tonsils, thymus, spleen and other lymphoid organs.

Neorickettsia helminthoeca

Prevention of Salmon poisoning in Dogs

• Restrict the ingestion of uncooked salmon, trout, steelhead, and similar freshwater fish.

• Animals that recover mount a persisting profound humoral immune response and are resistant to further infection but may serve as source of infection.

• N. elokominica- It is reported to be the cause of Elokomin fluke fever in canids, ferrets, bears, and raccoons. Dogs and other animals become infected by ingesting trout, salmon, or Pacific giant salamanders that contain the encysted metacercaria stage of the Rickettsia-infected fluke. In the dog's intestine, the metacercarial flukes excyst, embed in the duodenal mucosa, become gravid adults, and transmit the rickettsiae to monocytes-macrophages. The fluke infection itself produces little or no clinical disease but the Rickettsia may be cause of illness and death.

Orientia tsutsugamushiTsutsuga= Small & Dangerous + Mushi=Creature

• Scrub typhus/Rural Typhus/ Hairy Mite Fever/ Keelani Fever/ Japanese Fever/ Chigger borne typhus

• In India it is most common zoonotic Rickettsia infection

• A Vector (Trombiculid mites, Leptotrombidium deliense & L. akamushi) borne disease. Only larval stage of the mite can transmit the disease

• Scrub means a type of vegetation like abandoned plantation, rice field, forest clearing, river bank. It acts as Endemic Foci and these areas are known as mite islands.

• Wild rodents acts as natural hosts to Scrub Typhus and migration of the rodents leads to establishments of diseases in different foci but rodents themselves don’t show any clinical sign.

Scrub Typhus/Rural Typhus

World Scenario: Triangle of Scrub Typhus/Rural Typhus

Northern Japan to Far Eastern Russia

Northern Australia

Up to Pakistan & Afghanistan

Tsutsugamushi Triangle

1 billion population are at risk 1 million cases occurs annually

Parag Sharma, Rakesh Kakkar, Shilpa.N.Kaore,Vijay. K. Yadav, Raj Sharma. Geographical Distribution, Effect of Season & Life Cycle of Scrub Typhus.

Scrub Typhus/Rural Typhus in India

Prevalent all over India1. In Shivalik Ranges ( From Kashmir to Assam)2. Vindhya & Satpura Ranges in Central India3. Deccan Plateau in Southern India Eight serotypes are recognized [Gillian, Karp,

Kato, Shimokoshi, Kawaski, Kuroki, Litchfield (Australia)]

Clinical Signs of Scrub Typhus

• Eschar at the site of bite of mite (may lead to missing of diagnosis because in most of Indian cases eschar may be absent).

• It multiplies and develops inside phagocytes• Fever, headache, myalgia, dry cough, GI

disturbance are common.• Delayed Treatment may lead to complications

like renal failure, meningitis, myocarditis , pneumonia, multi organ failure.

Clinical cases reported across India

1. April2006- April 2008 (50 cases)2. February 2011-January 2012 (57 cases

3. Septmber2012-february 2013 (53 cases)In Pondicherry

June 2009-October 2010, 42 cases in Goa

August 2011- December 2012,176 cases in Andhra Pradesh

October- December 2012, 42 cases in North West India

In 2003, 43 cases in Himalayan RegionIn 2003-2004 & 2007, in Sikkim and Darjeeling

January 2004 to December 2005, 115 +ve cases, Seroprevalence (37.5%) in T&N

Environment Favouring Scrub Typhus/Rural Typhus

• Most of the cases occurs after July and before February i.e. during monsoon and during post-monsoon period.

• During monsoon period there is increased incidence of rain and exposure of rural people occurs during rice harvesting in fields.

• During post monsoon period there is increased scrub vegetation which is an important habitat or mites.

Problems of Controlling Scrub Typhus/Rural Typhus

• Lack of public knowledge/ education.• Poverty resulting in less hospital visits and

thus low number of case detection.• Diagnosis mostly done using Weil-Felix

reaction(High specificity & low sensitivity test)

• IFA, IPA & ELISA are not available in India at economic rates and are out of approach.

Murine Typhus

• Endemic typhus/ Urban typhus/ Shop typhus/ Flea Borne Typhus

• Causative agent – Rickettsia typhi (Previously known as R. mooseri)

• Vector- Mostly Rat flea (Xenopsylla cheopis) and rat louse (Polyplax spinulosa) but also Cat flea (Ctenocephalidis felis) and mouse flea (Leptopsylla segnis) may act as a vector.

Life Cycle and Transmission of Murine Typhus

• Normal life cycle Rat-flea-Rat.• Rat (Rattus rattus, R. norvegicus, R. exulans) acts as a

natural carrier (no symptoms /no clinical disease)• Also Shrews and Skunks acts as host.• Can persist long time in cat burrows.• Human is accidental host (vascular endothelial cells

resulting obliterative thrombo vasculitis & perivascular nodules)

• Virulent to Guinea pigs when experimentally inoculated produces Neil-Mooseri Reaction (Scrotal swelling, inflammation, haemorrhage beneath tunica)

Source of infection for Murine Typhus

• Inhalation of infected flea faeces.• Contact of infective excrements with

conjunctiva.• Swatting of flea while feeding or scratching

after bite.• Visit to hot humid area & cold semi arid area,

favourable foci/ niche of the disease.

Murine Typhus: Indian scenario

• Besides India, disease is common in China, Indonesia, Morocco, Canaries, Isles, Africa, Malaysia, Thailand and Myanmar.

• In India, Jammu and Kashmir, Himachal Pradesh, Uttar Pradesh (Lucknow), Karnataka (Mysore) and West Bengal (Kolkata), Maharashtra (Pune), Andhra Pradesh (Golkunda), Haryana (Karnal, Rewari) areas have been found infested wuith Murine Typhus.

• Most parts of in South India are endemic areas particularly during cooler months.

Indian Tick Typhus

• Also known as Boutonesee Fever/ Israeli Spotted Fever/ Mediterranean Spotted Fever.

• Caused by Rickettsia conori.• Transmitting vector is a tick, Riphicephalus

sanguineus.• Has a wide host range including wild rodents, sheep

& goats, non- human primates.• Up to 80% dogs are found to be serologically positive

without any clinical signs as observed in case of other animals.

Indian Tick Typhus in humans

• Small red dish shaped ulcer at the site of tick bite.

• Localized lymphadenitis, fever for 5-7 days, myalgia and joint pain.

• Generalized eruption after 4-5th days of fever.• Complication in some cases like purpuric

exanthema, renal failure, hypoxemia, thrombocytopenia, hypotension, hypocalcaemia may lead to mortality.

Indian Tick Typhus Occurrence

• Reported from Karnataka(Bangalore), Kerala, Uttar Pradesh (Allahabad, Lucknow, Jhansi), Maharastra(Pune), Andhra Pradesh (Narsapatnam, Secunderabad), Tamilnadu (Trichinapally), Madhya Pradesh (Ratlam) and West Bengal (Darjeeling).

• First reported in Foothills of Himalayas.• Out of total pyrexia of unknown origin (PUO), Rickettsial

diseases amount for nearly 24%. Out of total richettsial infection cases scrub typhus was responsible for 62.8%, spotted fever group for 32.6% and endemic typhus for 4.7% cases (Somashekar HR et. al., 2006).